As the transmission of compressed audio and video information over the Internet has become more widespread, practical methods for eliminating the mismatch between the clock used for encoding the information and the clock used for decoding the information has gained importance. This problem may be seen in systems where a head end in a cable office communicates content over an IP based network to a set-top-box (STB) in the home. Historically, cable and satellite systems have made use of a phase-locked loop (PLL) in the STB to recover the system clock and accordingly synchronize the STB with the head end. This approach may be typical of both cable and satellite networks.
Synchronization of the clocks may become more challenging where there may be a significant amount of latency in the network. For example, in an IP based network, where packets of data may be sent from a source device to a destination device, the amount of time it takes for a packet of data to arrive at a destination may be a function of the number of users using the network and the path taken by the packet of data. In this regard, the amount of latency in the network may not be constant and the amount by which the latency varies may be considered packet jitter. As a result of the packet jitter, it may become challenging to recover timing information used in the encoding process in the head end.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.